With their numerous excellent characteristics, blow molded bottle bodies made of polyethylene terephthalate (PET) resin (so-called pet bottles) are used as bottle body containers in a variety of fields.
Containers of such a kind are generally molded by expandingly stretching and deforming a preform that have been inject molded into a bottomed tubular shape in a state where the preform is heated to a temperature at which a stretching effect is achieved.
For example, as illustrated in FIG. 26 (which corresponds to FIG. 12 in Patent Literature 1), a preform 31 heated to a temperature at which the stretching effect is achieved is fitted to a blow metal mold 101, with a mouth tubular portion 32 of the preform 31 being projected upward and with a neck ring 33 being engaged with a neck support flange portion 103, the neck ring 33 being integrally formed around a lower end on an outer circumferential surface of the mouth tubular portion 32 of the preform 31. Then, a guide tubular portion 110, which is a tip portion of a blow nozzle 105, is loosely fitted into the mouth tubular portion 32 of the preform 31, and in this state, the preform 31 is stretched in an axis direction by means of a stretching rod 116 inserted through an insertion hole 111 formed through a middle of the blow nozzle 105 and is also stretched in a radial direction by means of blow air as a pressurized fluid through the insertion hole 111 so as to be molded into a bottle body 41.
Patent Literature 2 also discloses an invention of a method for blow molding a preform by using a liquid instead of blow air as the pressurized fluid. In the molding method, by using a content liquid that is to be filled in a final product as a liquid, a filling step may be omitted, and a production line may be simplified.